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SubjectRe: [PATCH 1/2 v3] dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller
On Fri, Jul 3, 2009 at 10:24 AM, Nicolas Ferre<> wrote:
> This AHB DMA Controller (aka HDMA or DMAC on AT91 systems) is availlable on
> at91sam9rl chip. It will be used on other products in the future.
> This first release covers only the memory-to-memory tranfer type. This is the
> only tranfer type supported by this chip.  On other products, it will be used
> also for peripheral DMA transfer (slave API support to come).
> I used dmatest client without problem in different configurations to test it.
> Full documentation for this controller can be found in the SAM9RL datasheet:
> Signed-off-by: Nicolas Ferre <>
> ---
> v2 is here:
> v2 -> v3:
>  - initial number of descriptors to allocate for each channel raised to 64 and
>   is now a parameter
>  - ack-bit in descriptor flag comment synchronized with TXx9 dma driver
>  - atc_desc_get() when short on descriptors in pool: create one at a time
>  - allocation flag changed to GFP_ATOMIC in atc_desc_get()
>  - call to proper funtion while unmapping: use of new
>  - call dma_run_dependencies() at the end of atc_chain_complete()

Looks good, but now I belatedly wonder if that GFP_ATOMIC should be
GFP_NOWAIT instead? Do we really want to consume from the system
emergency pools for these allocations (a similar fix is need for
ioatdma and fsldma)?

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